Peter Fincham, the television guru behind some of the most influential and popular shows of the past 15 years from The Bill to I'm Alan Partridge, yesterday promised to "reinvigorate" BBC1 after his appointment as controller of the channel.

The outgoing chief executive of independent production giant Talkback Thames was unveiled as the replacement for Lorraine Heggessey, who in a neat twist announced earlier this year that she was taking his current job.

"The BBC is going through big changes, but BBC1 remains its flagship channel and reinterpreting and reinvigorating it for new audiences is about as exciting as it gets," said Mr Fincham, who is likely to start in May when Ms Heggessey leaves the corporation.

He said he wanted to deliver "popular entertainment with a purpose", pointing to BBC1's upcoming Africa season and an Egypt season slated for the autumn as examples of that mission statement.

The job is recognised as one of the most difficult in television with its constant scrutiny from politicians and the press. Most pressingly, Mr Fincham will be forced to deal with the perception that in her mission to boost the popularity of the channel, Ms Heggessey leaned too far towards unashamed populism.

But Mr Fincham, who during his time at Talkback Thames oversaw a wide range of popular shows including Jamie's Kitchen, Pop Idol, Grand Designs and The Lost Prince, said it was important for the channel to retain the ambition to appeal to mass audiences.

"Not for a minute am I thinking of taking BBC1 down a road that abandons the mainstream.

"I know I will be asked about chasing ratings. Well, I certainly want to chase success. BBC1 needs to be a successful channel," he said.

"I don't think BBC1 gets less relevant and important, I think it gets more so. The big terrestrial channels that offer a full and varied menu of programmes become the rarer beasts."

His appointment, greeted with welcome surprise inside and outside the BBC, is the first time in more than 20 years that the corporation has appointed a controller of its flagship channel from outside the organisation.

"My appointment may be an example of the BBC becoming a more outward facing place. I think it's useful to bring in someone from the outside who's not from the BBC's world," he said.

Director general Mark Thompson has vowed to remove "derivative" and "formulaic" programmes from the schedule and invest heavily in original drama, comedy and popular factual programmes.

With a budget of more than £800m a year, Mr Fincham will have to walk the tightrope of combining ratings success with Mr Thompson's "building public value" mantra.

"A big theme will be partnership," he added, pointing to the forthcoming David Dimbleby series A Picture of Britain, made in conjunction with the Tate, and the BBC's avowed intent to be more transparent in dealing with the independent production sector.

BBC director of television Jana Bennett said that Mr Fincham was one the top 10 people who had shaped the medium over the past decade, adding that his outsider's eye would prove invaluable at a crucial time for BBC1.

Since founding Talkback with comedians Griff Rhys Jones and Mel Smith in 1985, he helped the company to grow into a TV production powerhouse producing over 850 hours of programmes a year.

The company was bought by Pearson for £62m in 2000, a move that netted Mr Fincham an estimated £20m, and was then taken over by German media giant RTL in 2003, when Talkback and Thames merged and he was made chief executive.

Last year, he narrowly missed out to then BBC marketing director Andy Duncan in the race to become chief executive of Channel 4, and was also considered for the chairman's role by Ofcom.

"He has a fantastic eye for talent, and is very good at spotting the highest quality ideas," said Ms Bennett, who awarded the job to Mr Fincham over internal candidates Alison Sharman, head of daytime, and Jane Lush, head of entertainment commissioning.

Dear Controller, what we want you to do...

Andrew Zein, Tiger Aspect (Vicar of Dibley, Murphy's Law) Please be ambitious and spend, spend, spend. With the largest budget of any UK channel you have the financial firepower to be ambitious in all areas.

Your BBC1 audience, being so broad and mainstream, loves the best talent. Grab the money that Mark Thompson has pledged to new comedy and drama and get the best.

Don't rely on other BBC channels finding your comedies. Commission your own - you have an open goal with no other UK channel commissioning pre-watershed sitcoms.

In drama, commission more longer running and returning series. One thing - ignore the idea that programme budgets can be cut and quality maintained - it can't.

Bring to BBC factual the same ambition and vision that were in the shows Talkback produced for Channel 4.

John Whittingdale MP, shadow culture secretary BBC1 is the flagship channel and should be at the heart of what the BBC stands for - high quality public service programming which is not only entertaining but also informative and educational.

I wish you every success but I hope you quickly put out of your mind the work you did in making Pop Idol and shows like that. You were also involved in The Lost Prince and that's absolutely an example of the sort of high quality drama the BBC should be making. I recently watched Archangel and that too was original, challenging drama.

It's a terribly important job - there's no shortage of programmes made by BBC1 which do not meet that public service remit. Less Fame Academy, certainly. And EastEnders is a whole different debate. I do, however, applaud the return of Doctor Who.

Steve Coogan, comedian, writer and producer BBC1 is not the all encompassing channel it once was. I echo Terry Wogan's comments. It shouldn't compete head-to-head, it should have a slightly different agenda.

Sometimes it's damned if it does and damned if it doesn't. Striking the right balance is difficult but can be done. Show a steady hand when things don't work. The BBC should be given a bit of leeway to fail.

When I'm in America I still brag about the BBC, about the leeway it gives programmemakers, and it needs to hold on to that. When programmes work they become part of the national conversation, that's more important and far more difficult than ratings alone.

It's the same with comedy, the best ones are those that capture the mood of the nation. The most recent example was Little Britain. That kind of comedy should be on the BBC. So more of that, please.

Eileen Gallagher, Shed Productions (Footballer's Wives, Bad Girls) If BBC1 doesn't keep its mass audience appeal, very soon it will not be able to justify itself. I think you'll strike the right balance between the popular and the innovative. They're not mutually exclusive. The BBC would never have had Morecambe and Wise if it wasn't populist.

You've got to stop scheduling aggressively against ITV and allow its innovative programmes space to grow too. I watched Head of the Class, an ITV drama about a failing school, and that's the sort of thing the BBC should be doing. It doesn't have to be worthy or boring - people have got to watch for entertainment first.

You've got to want it both ways - the best programming will entertain people and teach them something new. You'll fail more times than you succeed but you've got to try.

Will Wyatt, former BBC managing director BBC1 is the most important service that the BBC has. The most important thing is that it has to be popular, yet if you pick up the listings on any given day it must look like a BBC schedule. There may be things you don't watch or don't like, but you know why they're there.

You need to hold your nerve and do things which your instinct tells you will not be as popular as you want them to be but are important - be it arts or current affairs.

There was a time in the first two years of Greg Dyke's reign when BBC1 was racing along a populist course but the last 18 months have seen it pull back from that. It's in good shape.

Peter Kosminsky, writer and director The terms of the new charter specifically remove the obligation to compete for ratings. The success of the channel is to be judged by the quality, not the number watching. What more could an incoming controller ask for? You will have to apologise to no one for commissioning innovative and challenging programmes.

I hope you will take the opportunity to make a little mischief. The stronger the commercial imperatives, the greater the pressure to play safe (look at the last few years of poor old ITV).

With a 10-year charter, the BBC can afford to make programmes that the vested interests in our society find uncomfortable. I hope it will again become the home of opinionated film-making ... ready to tread less carefully and, occasionally, to tread on some plump, well-fed toes.